Transcript Movement Across cell Membranes
MOVEMENT ACROSS CELL MEMBRANES
Biology 9B - Dickson
Bio 9B: Friday, 12/9/11 Title:
Movement Across Cell Membranes
Homework: None – have a great weekend!
Silent Do Now (in NB w/ date & title)
What is the difference between “regular” diffusion and facilitated diffusion?
What do you think the cell membrane is made of?
What does it mean for the membrane to be “selectively permeable?
What is one thing you learned from doing the StarLogo computer lab?
Today’s Objectives
Describe how the structure of the membrane helps it to function
Describe and explain the following terms:
Lipid Bilayer Selective Permeability Diffusion Osmosis Facilitated Diffusion Active Transport Agenda:
Notes/Discussion Exit Ticket and Hand Back Work / Grades
Cell Membrane Structure
The cell membrane is made of…
Lipid Bilayer
Two layers of lipids that form the outer membrane of a cell.
Flexible Strong Do not Dissolve in water Proteins in the lipid bilayer Help transport molecules across the membrane
Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Cell Membrane Function
Selective Permeability
When a membrane only allows certain substances to pass across the membrane (and not others) Based on the size, shape, and charge (+/-/neutral) of the substances
Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Methods for Materials to Enter/Leave the Cell
Diffusion
Diffusion
Movement of molecules from a high concentration (more stuff) to low concentration (less stuff)
Spreading out so all areas have an equal concentration
Osmosis
Diffusion of water through a selectively permeable membrane Osmosis Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Methods for Materials to Enter/Leave the Cell
Facilitated Diffusion
When a substance diffuses through a membrane by going through a
protein channel
Regular diffusion goes through the lipid bilayer
Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Methods for Materials to Enter/Leave the Cell
Active Transport
When a substance is pumped across a membrane from where there’s a
low concentration to where there’s a high concentration (against the concentration gradient)
Opposite of diffusion
Requires a pump (made of protein) and
ATP energy!
Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Bio 9B: Monday, 12/12/11 Title: Diffusion Lab
Homework: Complete pages 3 and 5 of the lab packet.
Silent Do Now: Complete the worksheet.
Today’s Goals: You will be able to: Form a well-reasoned hypothesis about diffusion across membranes.
Test this hypothesis by following a lab procedure to perform an experiment Create a data table in order to organize and record your results.
Lab: Diffusion Across Cell Membranes
Model Cell w/ Dialysis Tubing Membrane
Water Objectives for Class:
Design an experiment by drawing from your knowledge of starch, glucose, cell membranes, and experimental indicators that test for the presence of starch and glucose.
Diffusion Lab: Procedure Review – Part 1
Set-up Dialysis Bag Moisten tube and tie one end Add the starch & glucose solution to the tube Tie the top of the tube Rinse w/ tap water to wash excess solution from outside of bag Set-up Beaker Fill a 250 ml beaker ¾ of the way with water Add Iodine to water – mixture should be orange Put dialysis bag into beaker with water and iodine
Water
and
Iodine Objectives for Class:
Design an experiment by drawing from your knowledge of starch, glucose, cell membranes, and experimental indicators that test for the presence of starch and glucose.
Diffusion Lab: Procedure Review – Part 3
Starch How do we test for it?
Use Iodine How do we know starch has passed through membrane?
Iodine
outside
purplish- brown the dialysis bag turns from yellow-orange to Glucose How do we test for it?
Boil it in Benedicts solution
or
use a glucose test strip How do we know glucose has passed through the membrane?
Glucose test strip will change color
Objectives for Class:
Design an experiment by drawing from your knowledge of starch, glucose, cell membranes, and experimental indicators that test for the presence of starch and glucose.
Expectations for Lab Work
Stay at your own table (no wandering) Talk quietly with members of your own group Stay focused on the lab!
Follow every step of the procedure Stay safe – use materials as instructed, no messing around
New Vocabulary
Diffusion, Osmosis and Selective Permeability In Action: http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Animation.htm
Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Bio 9B: Thursday 12/15/11 Title:
Diffusion Lab – Analysis & Conclusions
Homework:
Read pages 956-960. Answer questions on the back of the assignment sheet (write answers in notebook)
Silent Do Now (in notebook w/ title & date)
Copy the table on the board into your notebook.
Make it huge (fill the whole page of your notebook).
Fill in the first column (Results) by filling in each box with… Was there a color change? If so, describe!
Take out your lab packet and check your data table on page 4 if you can’t remember the results.
Today’s Objectives & Agenda: You will be able to:
Explain the results of the diffusion experiment Use the lab report rubric to identify mediocre versus excellent examples of Background Info sections Write or improve your own Background Info, Analysis, and Conclusion sections of your lab report Agenda:
Class Discussion of Results, Analysis, and Conclusions Evaluate examples of Background Info Class discussion & brainstorm for this lab’s Background Info
Time to type! And also to conference w/ Ms. Dickson about past assignments.
Diffusion Across Cell Membranes: Presenting the Data/ Results
Color Change?
Glucose Test Strip changed color Bag Turned Purple/ Black No Color Change to the Water Water
and
Iodine Objectives for Class:
Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Diffusion Lab: Analysis & Conclusions
RESULTS – Was there a color change? Describe!
ANALYSIS – What does this mean?
CONCLUSIONS Why did this happen? Does it support our hypothesis?
Dialysis Bag Water in Beaker Glucose Test Strip
Turned from white to
purple
No change (stayed orange) Turned from
green
to
brown green
Today’s Objectives & Agenda
Discuss and analyze the results of the diffusion experiment
Use the lab report rubric to identify mediocre versus excellent examples of Background Info sections Identify the strengths and areas for improvement in your own background info section Agenda:
Quick Class Discussion of Results
Evaluate examples of Background Info
Class discussion & brainstorm Peer editing
Lab: Diffusion Across Cell Membranes
Writing Better Background Information Sections
• •
Task 1 – Do this silently on your own:
• Read the two example Background Information sections from the Denatured Enzyme Lab Grade them according to the rubric.
Identify strengths and areas for improvement
Objectives for Class: Use the lab report rubric to identify mediocre versus excellent examples of Background Info sections
Sample Background Info sections
Example 1
Strengths: Contains scientific terms and definitions Things to improve: Unclear definitions Missing connections Awkward wording Topic sentence Overall grade: Fair
Example 2
Strengths: State purpose Explains all terms Good connections & examples “Because…” “However…” Things to improve: Add more vocabulary Overall grade: Excellent
Objectives for Class: Use the lab report rubric to identify mediocre versus excellent examples of Background Info sections
Diffusion Lab Background Info
1.
2.
Turn your lab packet to page 5 Your Tasks in A Small Group: Make sure everyone has descriptions of each word Make sure everyone has descriptions of two more words 3.
4.
Fill in the Connections part for each word by writing how it relates to at least one other word, or to the experiment At the bottom of that page, brainstorm some topic sentences to start off your Background paragraph 5.
Number each term in the chart based on the order you think you should introduce it in your Background paragraph
Your goal as a group is to help EVERYONE be ready to write an excellent Background Info paragraph!
Quiet Independent Work Time
Tasks to Work On: Continue writing your lab report (it is due Monday) Do tonight’s HW (book reading & questions) Conference w/ Dickson about past assignments or help on the lab report Small groups will come to work w/ Dickson on the Do Now from earlier this week
Work quietly and professionally Stay focused on biology.
No internet – it slows down everyone’s laptop!
Bio 9B: Friday12/16/11 Title:
Cell Membrane Vocabulary Application
Homework: Typed & completed lab report due Monday.
Silent Do Now – On an index card, not in your notebook!
Find the following definitions in your notebook and write them on an index card (all definitions on same card): Diffusion Osmosis Facilitated Diffusion Active Transport Today’s Objective: Apply these vocabulary words to various situations in living things – so that you can accurately identify examples and pictures of each process.
Instructions
Spend 3 minutes at each station Read the scenario, look at the pictures, read the questions Mark your answers on the answer sheet (do not write on the station handouts) Work with your assigned partner (next slide), talk quietly on with them, and stay focused on the work.
Partners
Cabinet Side of the Room
Justin—Jarred Ritshly—Kira Jenna—Skyeler—Tia Ronica--Naidaliz Sequoia—Steven—DJ
Window Side of the Room
Noah—Priscilla Nicole—Zak—Sara Destinee—Emily Aaron—Emperor Tracey-Natalie-Elizabeth
Exit Ticket
Work silently on your own to correct or finish your Do Now sheet from Monday If you don’t get your Do Now sheet back, complete the AP Biology test questions!